Such a tissue punch is known, for example, from DE-GM 7 817 220. This instrument is equipped with a receiving part, in which the separated tissue particles are caught and which can be screwed off the instrument for emptying.
DE-PS 3 630 203 shows a surgical tissue punch, which is equipped with a suction apparatus for removal of the separated tissue pieces. This instrument essentially comprises an outer tube and an inner tube axially movable therein. The inner tube is provided at its distal end with a laterally opening hollow chamber, bordered by a cutting edge facing the outer tube. The cutting edge is applied to the tissue to be treated by having tissue pieces reach into the hollow chamber. By movement of the inner tube, by means of a corresponding actuation device, against the outer tube, which has a counter cutting edge corresponding to the cutting edge of the inner tube, the tissue pieces extending into the hollow chamber can then be cut. With the suction apparatus the tissue pieces can be sucked through the inner tube and out of the operation area. Suction occurs by applying a vacuum impulse to the inner tube when the two above-mentioned cutting edges touch or overlap each other. The separated tissue piece moves in this manner from the instrument to the collecting basin.
The above-cited tissue punches are constructed as straight, rigid instruments and are therefore poorly or not at all suited for many operations, for example in the thorax, since it is often necessary to carry out operations in areas which are difficult to reach.
This is possible with a flexible instrument shaft according to DE-AS 1 019 048 for surgical instruments, which can also be used in connection with tissue punches. This instrument shaft essentially comprises a spring wire helix with a slide guide slipping thereinto and is equipped at its distal end with a connection piece for the connection of different operating mechanisms. The wire helix surrounds a thin-walled and flexible tube, which stiffens the wire helix. In this way the entire instrument shaft is flexible and can be brought into the needed shape prior to usage.
However, using this instrument shaft as a carrier of a tissue punch mechanism it is necessary to extract the instrument shaft with the punching mechanism from the operation area for removal of the separated tissue pieces.
There are also tissue punches according to EP-OS 0 445 918 and U.S. Pat. No. 4,646,738 where the outer shaft is rigid and extends from a proximal straight region to a distal curved region, while the inner shaft is flexible so that it can conform to the outer shaft at its curved region. The motorized rotating inner shaft can be axially adjusted in the outer shaft and with a cutting edge at its end can be brought in contact with the tissue to be separated. The tissue extends through an opening of the outer shaft into its inner area, and the separated tissue is siphoned off through the inner shaft.
Apart from the fact that longitudinal movements of cutting parts are generally more effective than rotational movements due to a longer "open phase," such cutting instruments have some further disadvantages. The means necessary to make the inner shaft flexible, for example material cutouts, give rise to an irregular surface of the shaft canal with the consequence that the separated tissue cannot be sucked hindrance-free and with low friction through the inner shaft. In addition, problems develop with the cleaning and hygienic treatment of the instrumentation. Furthermore, an eventual breakage of the inner shaft cannot be visually noticed, and it also creates problems to remove a distal fragment of the inner shaft from the outer shaft. Finally, the operator cannot observe the instantaneous position of the cutting tool due to its covered location.